This invention refers in general to machines for cleaning or classifying, sizing or screening grains, seeds, granular and powdery material, and more particularly concerns to improvements in a universal modular screening, classifying, cleaning and sizing machine which is adaptable to the conditions of each individual product, whether it be powdery, granular, vegetable or mineral, by means of regulating at will the stroke and frequency of the oscillation.
Up to the present time there has not been a universal machine which encompasses or covers the different processes of cleaning, sizing, classifying, etc. of various products as efficiently for each particular product as a machine specifically designed and built for a single one of the objectives mentioned.
At the present time there are very diverse types of machines designed and manufactured for each of the objectives indicated, but they are so specialized that the one used for cleaning grains is not suited for classifying seed for planting, nor will a machine for this purpose serve to sift powdery or floury products, nor is it suitable for separating minerals, and so forth.
For each one of these indicated operations a different oscillation and a different frequency of oscillation is required, ranging from a particular rectilinear oscillatory movement of the screens for certain specific cases to a rotary movement of the screens.
The best solutions have been obtained up to the present time in machines able to produce different kinds of oscillations ranging from circular movement at the point of delivery of the material to straight-line movement at the material discharge. However, this type of oscillation is obtained in fixed mechanisms machines with fixed stroke and frequency which transmit severe trepidation to their own structure, causing problems in mounting them because of the need for insulating them to prevent the transmission of such shaking to other machinery, as well as the resulting wear and deterioration which such continuous shaking produces in a machine. Furthermore, this kind of shaking makes its impossible to stack two or more of these machines in order to obtain the combination of operations required for the treatment of a product or material which is to be cleaned, screened, classified, sized or separated.
This latter type of machine, in addition to the drawbacks cited, can be easily differentiated from the one which is the object of the present invention by the fact that the oscillation is obtained by means of a fixed mechanism, that is, it is not of the freely oscillating type, to which the present invention belongs, preventing the posibility of frequency and stroke lenght modification.